This invention relates generally to a tool system for handling small parts and more particularly to improvements in hand held, pneumatically operated implements for picking up, placing, adjusting, or removing delicate or sensitive parts such as an electronic microelement to be affixed and connected to a circuit board or a larger integrated circuit chip to be affixed and connected with its many solder points to a circuit board. The term "pneumatic" means that forces due to a vacuum or to venturi effects are utilized for holding or lifting the part; and "hand held" is intended to include robotic applications.
In the development of modem microelectronics, the various elements and components incorporated into the assembly of a circuit as, for example, in a microprocessor, a computer, or controls for automated apparatus, have typically become smaller, more delicate and sensitive, more costly, and very critical in their exact placement, as on a circuit board, during assembly or manufacture or testing or repair or replacement. Consequently, it has become increasingly difficult, for example, to successfully and efficiently select a small part, pick it up, place it precisely, hold it during a soldering or other securing process, and then release it--all without placement or orientation error and without subjecting the part to unacceptable mechanical, thermal, or electrical stresses.
Prior art efforts have typically been directed toward mechanical holding techniques such as clamps, forceps, tweezers, or the like; and in some applications such approaches are satisfactory. However, holding a small part by mechanical measures have disadvantages of lack of reliability or of the part slipping away and being dropped. Further the mechanical strees caused by the tweezer compression can, for delicate parts, be intolerable. Further, such tools suffer a lack of versatility in exactly how and in what orientation it selects and picks up the part.
One non-mechanical approach has been to provide a hand held tool containing a spring loaded piston creating a vacuum chamber between the interior of the tool and a suction cup affixed to the nozzle end of the tool. When a part is to be picked up, the piston is pushed forwardly by a plunger or trigger toward the nozzle, the part is placed against the suction cup, and the piston released to create a holding vacuum by the spring. When the part is to be released, the plunger or trigger is again pushed forwardly to extinguish the vacuum within the chamber and the holding suction cup. Another version of this technique is to provide instead of a spring loaded piston within the chamber, a fountain pen type elongated bladder which is compressed by a trigger holding a vane against the side of the bladder to create a vacuum. Again, when the part is to be released, the vane against the bladder is pushed inwardly by the trigger and the holding vacuum is extinguished.
These prior art vacuum devices suffer from at least three limitations which for many modern applications constitute serious disadvantages: first, there is a limit to the magnitude or volume of the vacuum available due to the geometry of the piston chamber or bladder; second, some leakage is inherent and thus the holding time for such a device is limited such that its holding force is not constant, diminishes, and at an unknown moment the part may be released and be dropped; third, the necessity of "working" the piston to extinguish the holding vacuum may cause an unacceptable recoil or other displacement of the part just as it is being critically emplaced.
Another problem unsolved in this art has been to avoid thermal damage to a part while it is being emplaced or removed and its connecting solder points are necessarily being fused or reflowed by application of soldering heat.
It is an object of the present invention to provide a pneumatic handling implement for small parts which is not subject to these disadvantages and limitations of the prior art.
It is another object to provide such a tool which is light in weight and exceedingly easy to handle and operate.
It is another object to provide such a tool which operates from any common source of compressed air to create selectively its own vacuum, or venture air flow for lifting effects.
It is another object to provide such a tool whose various embodiments include holding features covering a wide range of shapes and sizes adapted to optimumly handle any small parts.
It is another object to provide such a tool which may supply coolant air for a part being held while being soldered.
It is another object to provide such a tool which may be readily adapted for utilization in robotic applications.